1. Field of the Invention
The present invention generally relates to a keypad. More particularly, the present invention relates to a keypad of a touch sensor type.
2. Description of the Related Art
A keypad for inputting characters and numbers and a keypad for selecting a direction for menu selection and cursor movement may be used for portable terminals, and a dome switch may be used for the keypad for direction selection. Recently, a thin keypad of a touch sensor type has been developed for use in compact and slim portable terminals.
FIG. 1 illustrates a conventional keypad 100 of a touch sensor type. Referring to FIG. 1, the keypad 100 includes a flexible resistive layer 110, a rigid resistive layer 120 facing the flexible resistive layer 110, an air gap 101 between the flexible resistive layer 110 and the rigid resistive layer 120, and support members 102a and 102b at both ends of the flexible resistive layer 110 and the rigid resistive layer 120.
Once the flexible resistive layer 110 is pressed by a user, a user's selection is detected and transmitted through a resistance change caused by the formation of a contact between the flexible resistive layer 110 and the rigid resistive layer 120. A keypad of an electrostatic capacitance touch sensor type that detects a position and a selection through a charge change caused by a user's touch has been suggested.
However, such a conventional keypad requires a separation interval for suppressing interference from adjacent keys and a pattern space at its edge, increasing the size of the keypad. Moreover, the conventional keypad may malfunction due to a sensitivity change.